DE102005019807B4 - Method and device for the localization of faulty components or leaks in the intake tract of an internal combustion engine - Google Patents

Abstract

Method for locating and isolating defective components or leaks in an intake tract (1) of an internal combustion engine, which has an air mass sensor (8) and an intake manifold absolute pressure sensor (12), wherein - the detection of a defective component or leakage by means of a comparison between the load of the internal combustion engine determined with the air mass sensor (8) or the intake manifold absolute pressure sensor (12) and the load (L_DK) determined on the basis of the position of a throttle valve (9); a further determination of the load of the internal combustion engine (L_BKM) is made via the position of the throttle valve (9) and the localization is based on a comparison of the value (λ_M) and measured with a lambda probe (6) in an exhaust gas tract (3) of the internal combustion engine of a lambda target value (? _S) and - To further narrow down the faulty component or leak, a comparison is made between the air mass (LM_LMS) measured with the air mass sensor (8) and the air mass (LM_SADS) calculated on the basis of the measured values of the intake manifold absolute pressure sensor (12).

Description

The present invention relates to a method and a device for the localization of faulty components or leaks in the intake tract of an internal combustion engine.

The load of an internal combustion engine can with the help of sensors such. As an air mass sensor or a Saugrohrabsolutdrucksensor, or be determined in dependence on the throttle position and the speed of the internal combustion engine. For gasoline engines usually both methods are used for load determination. The legislator prescribes in this case a plausibility check of the throttle position based on the load determined by means of sensors. If there is an impermissible deviation between the load determined by the sensor and the position of the throttle flap, then an erroneous component or leakage in the intake tract of the internal combustion engine must be assumed. Without the use of further information, the localization of the faulty component or leakage is not possible. So z. As a leakage in the intake, a defective throttle or a defective air mass sensor indistinguishable. By including the information from the fuel system diagnosis, such as. As the development of the lambda value, further conclusions on the possible fault location (air mass sensor to throttle, or throttle to intake valve) are possible. However, a precise distinction between a faulty component or leakage is not possible despite this additional information. Thus, the localization of the faulty component or leakage in the workshop must be done by a time-consuming and costly examination of the individual components.

• – Ermitteln des Druckes vor der Drosselklappe der Brennkraftmaschine;
• – Ermitteln des Druckes im Saugrohr der Brennkraftmaschine;
• – Bilden einer Druckdifferenz Δp durch Subtrahieren des Druckes im Saugrohr von dem Druck vor der Drosselklappe;
• – Vergleichen der Druckdifferenz Δp mit einem ersten Schwellenwert ΔP1 bei drosselfreiem Betrieb der Brennkraftmaschine und/oder mit einem zweiten Schwellenwert ΔP2 bei gedrosseltem oder ungedrosseltem Betrieb der Brennkraftmaschine; und
• – Detektieren, das mindestens einer der beiden Drucksensoren fehlerhaft ist, wenn Δp > ΔP1 und/oder Δp < ΔP2.

In the DE 102 46 320 A1 a method for detecting a defective intake manifold pressure sensor and / or a faulty ambient pressure sensor in a variable-displacement engine is known. The method comprises the following steps:

• - Determining the pressure in front of the throttle valve of the internal combustion engine;
• - Determining the pressure in the intake manifold of the internal combustion engine;
• - Forming a pressure difference Ap by subtracting the pressure in the intake manifold from the pressure in front of the throttle valve;
• Comparing the pressure difference Δp with a first threshold value ΔP1 with throttle-free operation of the internal combustion engine and / or with a second threshold value ΔP2 with throttled or unthrottled operation of the internal combustion engine; and
• Detecting that at least one of the two pressure sensors is faulty if Δp> ΔP1 and / or Δp <ΔP2.

From the DE 43 44 633 A1 a device for load detection with diagnosis in an internal combustion engine is known, in which a main load signal and a secondary load signal are filtered appropriately and run continuously plausibility studies in which the filtered main load signal is compared with limits and depending on the comparison results, a signal limitation and error detection. The limit values can be corrected and the signal limitation takes place in the entire operating range, the error detection, however, only in an operating range in which an error of the main load sensor, in particular caused by backflow error of the main load sensor does not occur.

In the DE 197 50 191 A1 For example, a method and apparatus for monitoring load sensing of an internal combustion engine is described, wherein an air mass flow signal is measured and a further air mass flow signal is calculated based on a throttle position signal. The two signals are compared with each other. For error monitoring, the adjusted signals are compared with each other, whereby an error is detected if the two signals deviate from one another impermissibly. For detected errors, a torque reduction and an error separation is performed.

The object of the invention is to provide a cost-effective method and a device for the localization of faulty components or leaks in the intake tract of an internal combustion engine.

The object is solved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized by a method and a device for locating faulty components or leaks in the intake tract of an internal combustion engine, wherein signals of further sensors are evaluated for determining the faulty component or leakage. The method is based on the idea of enabling the localization of a faulty component or leakage by including further sensors present in the intake tract of the internal combustion engine. For localization, in addition to the signals of an air mass sensor, the signals of a Saugrohrabsolutdrucksensors and possibly evaluated the signals of an ambient pressure sensor. The method is used when in the plausibility check between the sensory and with the help of the throttle position detected load of the internal combustion engine an impermissible deviation occurs and a result of the fuel system diagnosis is present.

After an impermissible deviation has occurred between the sensory and throttle position determined load, it is assumed that the location of the faulty component or leakage is that the throttle and throttle position detection are functioning properly. The determination of the load of the internal combustion engine is based on the throttle position. In the following, the result of the fuel system diagnosis, which considers the development of the lambda value, is used for error localization. If the difference between the value measured with the lambda probe and the lambda set value is within a permissible range, it follows that the throttle valve is functioning properly. It must therefore be a defective air mass sensor or a leak, which is located in the intake between the air mass sensor and the throttle. If the difference between the measured lambda value and the setpoint is outside the allowable range, the throttle is defective or there is leakage in the intake manifold between the throttle and the intake valve. For a more accurate limitation of the faulty components or leaks, a Saugrohrabsolutdrucksensor existing in the intake manifold is used. With the help of the measured Saugrohrabsolutdrucks and stored in maps swallowing characteristics of the internal combustion engine, the air mass flowing into the cylinder can be calculated. During steady-state operation of the internal combustion engine, the difference between the air mass measured with the air mass sensor and the air mass determined by means of the suction pipe absolute pressure sensor is determined. If this difference is within a permissible range, there is a defective throttle valve. In the other case, there is leakage in the intake pipe between the throttle valve and the location where the intake manifold pressure sensor is located.

The presented method for the localization of faulty components in the intake tract of an internal combustion engine has the advantage that expensive tests in the workshop for the purpose of determining the faulty component accounts. In the workshop, only the faulty component determined during the procedure has to be exchanged. Thus, the method, compared to a fault localization in the workshop, the time required for the determination of the faulty component and the cost is reduced.

In an advantageous embodiment of the invention, a built-in intake tract of the internal combustion engine ambient pressure sensor for testing the Saugrohrabsolutdrucksensors is used. For the test, the difference between the measured values of both pressure sensors is formed before the start of the internal combustion engine or during full load operation of the internal combustion engine. For these operating points, the pressure in the intake manifold is equal to the ambient pressure, or the ambient pressure minus a pressure drop, the z. B. can be stored in a map. If this difference exceeds a permissible range, the suction pipe absolute pressure sensor or ambient pressure sensor is diagnosed as defective. The above-described error limitation using the Saugrohrabsolutdrucksensors can then no longer be performed. If the difference is within the allowable range, the suction pipe absolute pressure sensor operates properly and error detection based on its measurements is allowed.

In a further advantageous embodiment of the invention, the adjustment of the model values of the intake tract, in the event that a Saugrohrmodell exists, terminated with the measurements of the air mass or Saugrohrabsolutdrucksensors, if in the plausibility check between the sensory and with the help of the throttle position determined load of the internal combustion engine impermissible deviation occurs. This measure avoids that the model values assume values which do not correspond to the physical conditions in the intake tract due to the comparison with signals of faulty sensors.

Embodiments of the invention are explained below with reference to the schematic drawings. Show it:

1 a schematic representation of an intake tract, a cylinder and an exhaust tract of an internal combustion engine,

2 a flowchart for carrying out the method according to the invention and

3 a flow diagram of an advantageous embodiment for testing a Saugrohrabsolutdrucksensors.

1 shows the schematic representation of an intake tract 1 an internal combustion engine, a cylinder 2 and an exhaust tract 3 , The over the intake tract 1 supplied combustion air passes through an inlet valve 4 into the combustion chamber of the cylinder 2 and from there, after combustion, via an exhaust valve 5 in the exhaust tract 3 , in the exhaust tract 3 there is a lambda probe 6 by which the residual oxygen content of the exhaust gas is measured and used to control the air-fuel mixture.

In the intake tract 1 There is an ambient pressure sensor 7 and an air mass sensor 8th for detecting the cylinder 2 supplied air mass. Furthermore, between the air mass sensor 8th and the cylinder 2 a throttle 9 to control the cylinder 2 supplied air mass attached. For this regulation, the opening angle of the throttle valve 9 via a throttle valve sensor 10 measured and the measured value to a control unit 11 fed. Furthermore, located between the throttle 9 and the inlet valve 4 a Saugrohrabsolutdrucksensor 12 , For the localization of the faulty component, the signals of all sensors are the control unit 11 fed. As a control unit 11 for fault location can z. B. the engine control unit can be used. For carrying out the method according to the invention, the following are in 1 used sensors: the throttle position sensor 10 , the lambda probe 6 , the air mass sensor 8th and the Saugrohrabsolutdrucksensor 12 , Based on the signals from the ambient pressure sensor 7 the additional possibility exists the plausibility of the signals of the Saugrohrabsolutdrucksensors 12 to consider.

2 shows a diagram illustrating the method for the localization of a faulty component or leakage. Initially, in step S1, the difference between the with the air mass sensor 8th determined load of the internal combustion engine L_LMS and calculated based on the throttle position load L_DK formed. If the amount of this difference is less than or equal to a limit value G1, there is no faulty component or leakage in the intake tract 1 and the process branches to the beginning in step S2. In the other case, there is an erroneous component or leakage, and in step S3, the load L_DK calculated based on the throttle position is set as the load of the engine L_BKM. The calculations of the load of the internal combustion engine L_BKM and the amount of fuel to be injected is now based on the throttle position.

Subsequently, in S4, the result of the fuel system diagnosis is used by taking the difference between that with the lambda probe 6 measured residual oxygen content λ_M in the exhaust gas tract 3 and the lambda setpoint λ_S is formed. If the amount of the difference is less than or equal to a threshold value G2, there is a defective air mass sensor 8th or leakage in the intake tract 1 between air mass sensor 8th and the throttle 9 in front. In step S5 we enter the diagnosis "air mass sensor 8th Defective LMS_d "or" Leakage in the intake tract between air mass sensor 8th and throttle 9 LE_LMS_DK ". If the amount of the difference exceeds the limit value G2, the diagnosis "throttle valve 9 or throttle sensor 10 Defective DK_d, DKS_d "or" Leakage in the intake tract 1 between throttle 9 and inlet valve 4 LE_DK_ELV ".

Subsequently, it is checked in S7 whether a Saugrohrabsolutdrucksensor 12 in the intake tract 1 there is SADS_ ?. If the result is negative, the diagnosis is made in step S8 that no further limitation KWF of the faulty component is possible. In the other case, it is checked in step S9 whether the amount of the difference between the reference to the Saugrohrabsolutdrucksensors 12 calculated air mass LM_SADS and with the air mass sensor 8th measured air mass LM_LMS exceeds a limit G3. If the limit value G3 is exceeded, the diagnosis of a leakage LE_DK_SADS in the intake tract takes place in the step S10 1 between throttle 9 and suction tube absolute pressure sensor 12 , In the other case, the diagnosis is made in step S11 that the throttle valve 9 or the throttle sensor 10 defective are DK_d, DKS_d.

In 3 is a flow diagram of an advantageous embodiment for testing the Saugrohrabsolutdrucksensors 12 shown. The steps S1 to S6 are performed according to the in 2 Process shown and are in 3 not shown anymore. In step S7, it is checked whether a Saugrohrabsolutdrucksensor 12 in the intake tract 1 there is SADS_ ?. If the result is negative, the diagnosis is made in step S8 that no further delimitation of the faulty component is possible KWF. For the other case, it is checked in step S12 whether an ambient pressure sensor 7 is there UDS_ ?. If no ambient pressure sensor 7 is present, in step S13, the branch is made to the in 2 The illustrated step S9 and the other steps are performed according to the in 2 processed process. If the ambient pressure sensor 7 is present, in step S14, the amount of the difference between the measured value P_UDS of the ambient pressure sensor 7 and the measured value P_SADS of the Saugrohrabsolutdrucksensors 12 educated. This difference is more conveniently carried out before starting or under full load of the internal combustion engine, since under these conditions, the pressure in the intake manifold corresponds to the ambient pressure. If the amount of this difference exceeds a limit value G4, the diagnosis is made in step S15 that the suction pipe absolute pressure sensor 12 or the ambient pressure sensor 7 Defective are SADS_d, UDS_d. In the other case, in step S16, the branch is made to the in 2 The illustrated step S9 and the other steps are performed according to the in 2 processed process.

Claims (4)

Method for locating and confining defective components or leaks in an intake tract ( 1 ) of an internal combustion engine having an air mass sensor ( 8th ) and a Saugrohrabsolutdrucksensor ( 12 ), wherein - the detection of a faulty component or leakage by a comparison between the with the air mass sensor ( 8th ) or the Saugrohrabsolutdrucksensor ( 12 ) determined load of the internal combustion engine and based on the position of a throttle valve ( 9 ) determined load (L_DK), - a further determination of the load of the internal combustion engine (L_BKM) on the position of the throttle valve ( 9 ) and the localization based on a comparison of the with a lambda probe ( 6 ) in an exhaust tract ( 3 ) of the internal combustion engine measured value (λ_M) and a lambda setpoint (λ_S) takes place and - for further delimitation of the faulty component or leakage, a comparison between the with the air mass sensor ( 8th ) measured air mass (LM_LMS) and based on the measured values of the Saugrohrabsolutdrucksensors ( 12 ) calculated air mass (LM_SADS) is performed. A method according to claim 1, characterized in that a check of the Saugrohrabsolutdrucksensors ( 12 ) by comparing between the measured values (P_SADS) of the suction tube absolute pressure sensor ( 12 ) with the measured values (P_UDS) of an ambient pressure sensor ( 7 ) he follows. Method according to one of the preceding claims, characterized in that a comparison of the model values of the intake tract ( 1 ) with the measured values of the air mass ( 8th ) or Saugrohrabsolutdrucksensors ( 12 ) is terminated if an impermissible deviation between the air mass ( 8th ) or Saugrohrabsolutdrucksensors ( 12 ) determined load of the internal combustion engine and based on the position of the throttle valve ( 9 ) detected load (L_DK) occurs. Device for locating and confining defective components or leaks in an intake tract ( 1 ) of an internal combustion engine having an air mass sensor ( 8th ) and a Saugrohrabsolutdrucksensor ( 12 ), having means which - faulty components or leaks by a comparison between the with the air mass sensor ( 8th ) or the Saugrohrabsolutdrucksensor ( 12 ) determined load of the internal combustion engine and based on the position of a throttle valve ( 9 ) detected load (L_DK), - a further determination of the load of the internal combustion engine (L_BKM) on the position of the throttle valve ( 9 ) and the localization based on a comparison of the with a lambda probe ( 6 ) in an exhaust tract ( 3 ) of the internal combustion engine measured value (λ_M) and a lambda setpoint (λ_S) and perform - for further delimitation of the faulty component or leakage a comparison between the with the air mass sensor ( 8th ) measured air mass (LM_LMS) and based on the measured values of the Saugrohrabsolutdrucksensors ( 12 ) calculated air mass (LM_SADS).

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